Cannot Use Callback; Call Forward All Error Message; Unresponsive Phone - Cisco 7975G Software Manual

Troubleshooting
Cause
You are disconnected from a call that you joined using Barge if the call is put on hold, transferred, or turned
into a conference call.
Solution
Barge into the call again.

Cannot Use CallBack

Problem
CallBack fails.
Cause
The other party might have Call Forward enabled.

Call Forward All Error Message

Problem
The phone shows an error message when you attempt to set up Call Forward All.
Cause
Your phone may reject your attempt to set up Call Forward All directly on the phone if the target number that
you enter would create a Call Forward All loop or would exceed the maximum number of links permitted in
a Call Forward All chain (also known as a maximum hop count).
Solution
Contact your system administrator for details.

Unresponsive Phone

Problem
The phone screen appears blank and the Display button is not lit.
Cause
The phone is powered down (sleeping) to save energy.
Solution
The phone will power up (wake) when the system sends the wake up message. You cannot wake the phone
before its scheduled power up time.
Cisco Unified IP Phone 7975G, 7971G-GE, 7970G, 7965G, and 7945G User Guide for Cisco Unified Communications
Cannot Use CallBack
Manager 9.0 (SCCP and SIP)
105